An endoilluminator system has an endoilluminator probe that projects light to illuminate a target, such as an interior region of a part of a human (e.g., an eyeball) or other organism. For example, an endoillumination system may include an illumination console in addition to the endoilluminator probe. The illumination console houses a light source and optics that focus light from the source onto a connector port. The endoilluminator probe has a proximal end that connects to the illumination console at the port and a distal end that projects illuminating light. The output of the endoilluminator system describes the output at the distal end of the endoilluminator probe. Information regarding the endoilluminator output can be important to the user. For example, in vitreoretinal surgery, the amount of light is controlled to avoid excessive exposure to the retina. Certain known endoilluminator systems, however, fail to provide a technique for calculating the endoilluminator output that is accurate and efficient in certain situations.